Type Design of. Bridge on NPCIL Channel

Name of Work: -NPPCL

Internal size off Box

= 3.05 m

2.6 m

Outer size off Box

= 3.85 m

3.4m

3.45 Center 3m

Assume 3.90 M thick earth on Box

Assume Density of Soil

= 20 KN/M3Assume Angle of internal friction of soil, = 30

So, coefficient of active earth pressure, CA= 0.297

Assume L.L. on Box

= 700 KN/M2

65.876 KN/M2Dispersed LL on slab

= 700/4.8x4.135.57 KN/M2Assume Density of Reinforced c.con.

= 25 KN/M3Assume density of PCC

= 22 KN/M3Assume thick of base conc.

= 0.15 m

Assume size of fillet

= 0.15 m

Assume thickness of earth

= 1.2 m1.2+0.2

1.4

Assume thickness of W.C. (M-25)

= 0.04 M

Assume thickness of RCC (M-25) Barrel

= 0.4 m0.2

Earth pressure on side of RCC Box

Due to surcharge

0.297*20*1.4

8.316 say9 KN/M

Due to semi saturated earth fill 0.297*20*3

17.82 say18 KN/M

Total earth pressure as base 8.316+17.82

26.136 say 27 KN/M

Load of Top SlabNote-1: Has the earth cushion rise the live load will get dispersed accordingly without changing the loading parameters. Dead load of earth fill= 1.2x20= 24

L.L. on slab

= 35.57 say= 36

Self weight of top slab= 25*0.4= 10

Total load on top slab = 1.65+10+36

69.57 say80 KN/M2Note-2: If the top slab is without the earth cushion, the L.L. + 25% impact load will be less than 80 KN/M2Upward pressure on bottom slab: taking per meter length of barrel

Load on top slab

= 80*3.85*1

308

Load of side wall

= 2*0.4*2.6*25

52

Load of 4 No. fillets

= 4*0.5*0.15*0.15*25*11.13

Load on bottom slab= 3.85*0.4*25

38.5

Load of 0.075 m thick WC= 3.05*0.075*22

0

Total weight 1.0 long barrel = 308+52+1.13+38.5+0399.63

Upward pressure

= 399.63/3.85

103.8

Net upward pressure = 103.8-0.4*2593.8 Say95 KN/M

Fixed End Method

MFab

= W1L2/12

-80*3.45^2/12

= -79.35

MFba

= W1L2/12

80*3.45^2/12

= -79.35

MFad

= W3L2/12+W4L2/309*3^2/12+18*3^2/30

= 12.15

MFbc

= W3L2/12+W4L2/30-9*3^2/12+18*3^2/30

= -12.15

MFdc

= W2L2/12

95*3.45^2/12

= 94.23

MFcd

= W2L2/12

-95*3.45^2/12

= -94.23

MFda

= W3L2/12+W4L2/20-9*3^2/12+18*3^2/20

= -14.85

MFcd

= W3L2/12+W4L2/209*3^2/12+18*3^2/20

= 14.85

BM in mid span of: -

Sagging M at top slab: -

Mamber A-B

= 80*3.45^2/8-46.94

= 72.085

Sagging M at bottom slab: -

Mamber D-C

= 95*3.45^2/8-59.106

= 82.236

Design Constant: Using M-25 & FE 415/500

CBC

= 8.5 N/MM2 st

= 150 N/MM2 For water retaining structure

1:-M

= 280/3.cbc= 280/3*85

= 10.98

2:-N

= m.cbc/m.cbc+st = 10.98*8.5/10.98*8.5*150= 0.38

3:- j

= 1-n/3

= 1-0.38/3

= 0.873

4:-Q

= cbc/2*n*j

= 8.5/2*0.38*0.873

= 1.41 N/MM2Req.

= M/Q.B

= 82.236*10^6/1.41*1000 82236000/1410

58323.4

= 241.5024 MM

Deff. = 400-40-10= 350 MM

Provide Steel:

So,

Ast DC

= M/ st.j.d=82.236*10^6/150*0.873*350

= 82236000/45832.5

= 1794.27 mm2

Ast AB= M/ st.j.d= 72.085*10^6/150*0.873*350

= 72085000/45832.5

= 1572.792 mm2Ast A

= M/ st.j.d= 46.94*10^6/150*0.873*350

= 46940000/45832.5

= 1024.164 mm2Ast D

= M/ st.j.d= 59.106*10^6/150*0.873*350

= 59106000/45832.5

= 1289.609 mm2Spacing of 20 dia bar:Top slab (bottom face) 314*1000/1572.79= 199.65

=20 mm dia @ 150 mm C/C

Bottom slab (top face) 314*1000/1794.27= 175

= 20 mm dia @ 150mm c/c

Spacing of 16 mm dia bar:-

Side wall:201*1000/1289.61

= 155.86

= 16 mm dia @150 mm mm c/c

Min. tension steel: -0.85 BD/500

= 595 mm2

= 595 mm